The invention pertains to an objective lens exchanging arrangement in a microfilm reader apparatus. Such an arrangement is, for example, described in a German published patent application No. OS 2750458, published May 17, 1979, which corresponds to U.S. Pat. No. 4,215,915. An adjusting ring must be swung into a predetermined position for exchanging the objective lens in this known arrangement until the objective lens can be upwardly pulled out of the objective lens tube. There is, however, generally mounted in the conventional microfilm reading apparatus a deviating reflecting mirror immediately above the objective lens. Such an arrangement makes it difficult to gain access to the space immediately above the objective lens tube so that additional measures are necessary to permit an unencumbered objective lens exchange. For example, in German published application No. OS2808443, published Aug. 30, 1979, there is disclosed an arrangement in which the hood of the reader can be swung backwardly, whereby the space above the objective lens tube becomes accessible when the hood is so swung backwardly. An other arrangements for improving the accessability to the objective lens tube is described in German published application No. OS2632934, published Jan. 26, 1978, which corresponds to U.S. Pat. No. 4,244,641. In this known arrangement the objective lens tube is mounted on a sliding support arrangement in the microfilm reader. This sliding support arrangement is pulled out or pushed in for purposes of exchanging the objective lens.
The afore-described known arrangements for facilitating the exchange of the objective lens have proven not to be fully satisfactory, because they are either too complex or too difficult to operate.